Systems and methods for determining tissue type

Abstract

Ablation and visualization systems and methods to access quality of contact between a catheter and tissue are provided. In some embodiments, a method for monitoring tissue ablation of the present disclosure comprises advancing a distal tip of an ablation catheter to a tissue in need of ablation; illuminating the tissue with UV light to excite NADH in the tissue, wherein the tissue is illuminated in a radial direction, an axial direction, or both; determining from a level of NADH fluorescence in the illuminated tissue when the distal tip of the catheter is in contact with the tissue; and delivering ablation energy to the tissue to form a lesion in the tissue.

What is claimed is: 
     
       1. A method for monitoring tissue ablation comprising:
 receiving light returned from a tissue; and 
 generating a graph of at least one of a collagen peak indicative of an amount of collagen in the tissue and an NADH fluorescence peak indicative of an amount of myocardium in the tissue, wherein a wavelength of the collagen peak is indicative of a relative amount of collagen and myocardium in the tissue; 
 displaying the graph representing the relative amount of collagen and myocardium in the tissue for the selection of an ablation strategy for a lesion formation in the tissue, the ablation strategy including the selection of one or more of an ablation energy type, an ablation energy power, duration of delivery of ablation energy, and ablation temperature limits of the ablation energy. 
 
     
     
       2. The method of  claim 1 , further comprising adjusting a location of the ablation of the tissue based on the determined tissue composition. 
     
     
       3. The method of  claim 1 , wherein the tissue is illuminated with light having a wavelength between about 300 nm and about 400 nm. 
     
     
       4. The method of  claim 1 , wherein the step of determining comprises monitoring a level of the light returned from the tissue having a wavelength between about 375 nm and about 575 nm to identify the NADH fluorescence peak and the collagen fluorescence peak. 
     
     
       5. The method of  claim 1 , wherein the distal tip is configured to deliver ablation energy in the form of electroporation energy. 
     
     
       6. The method of  claim 1 , wherein the ablation energy type is selected from the group consisting of radiofrequency (RF) energy, microwave energy, electrical energy, electromagnetic energy, cryoenergy, laser energy, ultrasound energy, acoustic energy, chemical energy, thermal energy and combinations thereof. 
     
     
       7. The method of  claim 1 , wherein the catheter comprises a catheter body; the distal tip being positioned at a distal end of the catheter body for delivering ablation energy to the tissue, and one or more optical fibers extending through the catheter body into the distal tip, the one or more optical fibers being in communication with a light source to illuminate the tissue and a light measuring instrument to relay the light returned from the tissue to the light measuring instrument. 
     
     
       8. The method of  claim 1 , further comprising illuminating the tissue in a radial direction and an axial direction with respect to a longitudinal axis of the catheter. 
     
     
       9. The method of  claim 1 , further comprising providing a real time visual feedback about the lesion formation by displaying a level of NADH fluorescence. 
     
     
       10. The method of  claim 1 , wherein the ablation energy is applied when an NADH fluorescence peak is detected. 
     
     
       11. The method of  claim 1 , further comprising performing an ultrasound evaluation of the tissue in combination with monitoring the level of NADH fluorescence. 
     
     
       12. The method of  claim 1 , further comprising determining a normalized magnitude of a level of NADH fluorescence and displaying variations in an actual magnitude of the level of NADH fluorescence to the normalized magnitude of the level of NADH fluorescence. 
     
     
       13. A system for monitoring tissue ablation comprising:
 a catheter comprising:
 a catheter body; and 
 a distal tip positioned at a distal end of the catheter body; 
 an ablation system in communication with the distal tip to deliver ablation energy to the distal tip; 
 a visualization system comprising a light source, a light measuring instrument, and one or more optical fibers in communication with the light source and the light measuring instrument and extending through the catheter body to the distal tip, wherein the one or more optical fibers are configured to pass light to a tissue and collect light returned from the tissue; and 
 a processor in communication with the light measuring instrument, the processor being programmed to: 
 receive data relating to the light returned from the tissue illuminated with the light from the light source; 
 generate a graph of at least one of a collagen peak indicative of an amount of collagen in the tissue and an NADH fluorescence peak indicative of an amount of myocardium in the tissue, wherein a wavelength of the collagen peak is indicative of a relative amount of collagen and myocardium in the tissue, and 
 display the graph representing the relative amount of collagen and myocardium in the tissue for the selection of an ablation strategy for a lesion formation in the tissue, the ablation strategy including the selection of one or more of an ablation energy type, an ablation energy power, duration of delivery of ablation energy, and ablation temperature limits of the ablation energy. 
 
 
     
     
       14. The system of  claim 13 , wherein the location of the delivery of energy by the ablation system is adjusted based on the determine tissue composition of the tissue. 
     
     
       15. The system of  claim 13 , wherein the processor is further programmed to monitor the level of NADH fluorescence during the delivery of ablation energy to determine stability of contact between the distal tip and the tissue. 
     
     
       16. The system of  claim 13  wherein the tissue is illuminated with light having a wavelength between about 300 nm and about 400 nm. 
     
     
       17. The system of  claim 13  wherein the processor monitors a level of a light returned from the tissue having a wavelength between about 375 nm and about 575 nm. 
     
     
       18. The system of  claim 13  wherein the catheter is configured to illuminate the tissue in a radial direction and an axial direction with respect to a longitudinal axis of the catheter. 
     
     
       19. The system of  claim 13  wherein the catheter further comprises one or more ultrasound transducers and one or more electromagnetic location sensors and the system further comprises an ultrasound system in communication with the one or more ultrasound transducers for ultrasound evaluation of the tissue. 
     
     
       20. The system of  claim 13  wherein the catheter further includes one or more electromagnetic location sensors and the system further includes a navigation system in communication with the one or more electromagnetic location sensors for locating and navigating the catheter. 
     
     
       21. A method for monitoring tissue ablation comprising:
 receiving light returned from a tissue; 
 generating a graph of a collagen peak indicative of an amount of collagen in the tissue; and 
 displaying the graph representing the amount of collagen in the tissue for the adjustment of one or more characteristics of ablation parameters based on the amount of collagen in the tissue for a lesion formation in the tissue, the ablation parameters including at least one of an ablation energy type, an ablation energy power, duration of delivery of ablation energy, and ablation temperature limits of the ablation energy. 
 
     
     
       22. The method of  claim 21 , wherein the step of determining a tissue composition further comprises identifying an NADH fluorescence peak indicative of an amount of myocardium in the tissue. 
     
     
       23. The method of  claim 22 , further comprising determining a relative amount of collagen and myocardium in the tissue. 
     
     
       24. The method of  claim 21 , wherein the ablation parameters comprise a location of the ablation of the tissue based on the determined tissue composition. 
     
     
       25. The method of  claim 21 , wherein the tissue is illuminated with light having a wavelength between about 300 nm and about 400 nm. 
     
     
       26. The method of  claim 21 , wherein the ablation energy type is selected from the group consisting of radiofrequency (RF) energy, microwave energy, electrical energy, electromagnetic energy, cryoenergy, laser energy, ultrasound energy, acoustic energy, chemical energy, thermal energy, electroporation energy and combinations thereof. 
     
     
       27. A system for monitoring tissue ablation comprising:
 a catheter comprising:
 a catheter body; and 
 a distal tip positioned at a distal end of the catheter body; 
 an ablation system in communication with the distal tip to deliver ablation energy to the distal tip; 
 a visualization system comprising a light source, a light measuring instrument, and one or more optical fibers in communication with the light source and the light measuring instrument and extending through the catheter body to the distal tip, wherein the one or more optical fibers are configured to pass light to a tissue and collect light returned from the tissue; and 
 a processor in communication with the light measuring instrument, the processor being programmed to: 
 receive data relating to the light returned from the tissue illuminated with the light through the distal tip of the catheter; 
 generate a graph of a collagen peak indicative of an amount of collagen in the tissue, and 
 display the graph representing the amount of collagen in the tissue for the adjustment of one or more characteristics of ablation parameters based on the amount of collagen in the tissue for a lesion formation in the tissue, 
 wherein the characteristics including at least one of an ablation energy type, an ablation energy power, duration of delivery of ablation energy, and ablation temperature limits of the ablation energy. 
 
 
     
     
       28. The system of  claim 27 , wherein determining the tissue composition includes identifying an NADH fluorescence peak indicative of an amount of myocardium in the tissue to determine a relative amount of collagen and myocardium in the tissue.